Journal of Nannoplankton Research , 25, I, 2003 .

W Wei: Upper Miocene biostratigraphy... , p. 17 - 23 .

UPPER MIOCENE NANNOFOSSIL BIOSTRATIGRAPHY ANDTAXONOMY OF EXXON CORE CH30-43-2 FROM THE
GULF OF MEXICO
WuchangWei
PaleoServe, 4389 Carte De La Fonda, San Diego, CA 92130 &Dept. ofGeosciences, Florida State University, Tallahassee, FL 32306; wei@paleoserve.com

Key words: nannofossil, Miocene, taxonomy, biostratigraphy, Gulf of Mexico
Abstract: Exxon Core CH30-43-2 from the NE Gulf of Mexico yielded very abundant and well preserved
Upper Miocene calcareous nannofossils. The succession of the nannofoss il events established for thi score provides some useful in formation toward an improved biostratigraphic scheme in the Gulf of
Mexico. Some new taxonomic observations were made, which include the description of three new
species (Discoaster pentabollii n. sp., Discoaster styzenii n. sp. and Discoaster wisei n. sp.), two newsubspecies (Discoaster berggrenii berggrenii n. subsp. and Discoaster berggrenii extensus n. subsp.), andamend ment of two species (Discoaster prepentaradiatus and Discoaster neohamatus).

86°24.7'W, in a water-depth of 1351m, and spot-cored to
the Middle Eocene. There is a coring gap of about 18m
above and below Core CH30-43-2. Above the core lies theUpper Pliocene and below the.core lies the Lower Miocene.
This study concentrates on the apparently complete Upper
Miocene Core CH30-43-2.
Smear-slides were examined with a lightmicroscope at a magnification of 1OOOx. The abundance of
selected nannofossil taxa on each slide was estimated using
the following criteria: V = very abundant, more than 10
specimens per field of view (fov); A= abundant, 1-10
specimens per fov; C = common, 1 specimen per 2-10 fov ;F = few, 1 specimen per 11-50 fov; R = rare, 1 specimen per
51-200 fov. For preservation of nannofossil assemblages,
G = good, little evidence of etching or overgrowth.
The bibliographic references of the species usedin this study can be found in Perch-Nielsen (1985) or Bown
(1998). Those not given in Perch-Nielsen (1985), that is,
Discoaster bergenii Knuttel et al. (1989) andReticulofenestra rotaria Theodoridis (1984) are given in
the references of this paper. New species and subspecies
are discussed below. Numerical ages discussed in thispaper refer to the time-scale ofBerggren et al. ( 1995).

1. Introduction
Nannofossil biostratigraphy haS' become ever more
important in the Gulf ofMexico, as there are more petroleum
drilling activities there than in any other comparable ocean
basin (http: // images .pennnet.com/ articles/ os/ cap/
cap_ 100187 .gif). However, only a few Miocene nannofossil
studies have been published for the Gulf of Mexico (e.g.
Gartner et al., 1983;Aubry, 1993) and it is highly desirable
to improve nannofossil taxonomy and biostratigraphy inthis important basin. Exxon Core CH30-43-2, recovered fromthe NE Gulf ofMexico (Figure 1), offers a good opportunity
for taxonomic and biostratigraphic study, as Core CH3043-2 contains very abundant and well-preserved Upper
Miocene nannofossils. Weiterman (1989) studied two
samples from this core. The current study attempts tocontribute more-detailed nannofossil taxonomic andbiostratigraphic information.

2. Materials and methods
Exxon Corehole CH30-43 was drilled in the NEGulfofMexicoin the early 1960s by Exxon and a consortium of oilcompanies. The corehole was located at 28 °01.1 ' N ,3o•

3. Biostratigraphy
The distribution of selected nannofossil taxa in Core CH3043-2 is presented in Table 1. As the samples were originallytaken and recorded in feet and inches, they have been
converted to metres in the second column, with the original
sample notations listed in the third column for easycomparison.
The nannofossil succession found in Core CH3043-2 is generally consistent with that prescribed in someof the latest zonation schemes, for example, Young (1999).
Current data, together with the generalised zonation
scheme of Young (1999), suggest that the following
nannofossil events may be applicable in the Gulf of Mexico(Figure2):
the top of Discoaster quinqueramus at 5.6Ma. Thiso·Figure 1: Location map of Exxon Corehole CH30-43

17

W Wei: Upper Miocene biostratigraphy. .. , p. 17 - 23.

Journal of Nannoplankton Research , 25, I, 2003 .

Q,),..-...

0
N

"-'

.-..

....

=
.c
=
<I)

<I)
<I)

.£

8
-;

c

Q,)

...=

0

=
=
z
c:l

0.00-0.33 0'0 11 -0'1 11
CN9b 0.46-0.48 1'6 11 -1'7 11
0.91-0.94 3'0 11 -3'1 11
1.37-1.40 4'6 11 -4'7 11
11

VGR
VG R R
VG
R
V G

C

c

11

CN a 1.85-1.88 6'1 -6'2
V G
9
11
11
V G
2.29-2.31 7'6 -7'7
V G
2.95-2.97 9'8 11 -9'9 11
CN8b 3.35-3.38 11'0 11 -11'1 11 VG
CN8a 3.78-3.81 12'5"-12'6 11 V G
CN7b 4.27-4.29 14'0 11 -14'1 11 V G

R
F
R
R
R
R

C F
F F C
F C A

c

C R

R

R F

R
R
R
F
F
F

F
F
F
F
R

R
R
R

ARC
ARC
C R F

c
c

F
F
F R F

C
R F

C R

F

R

F
R

c
c

R

F F

c
c
c

Table 1: Distribution of selected nannofossils in Exxon Core CH30-43-2 . V = very abundant; A= abundant; C = common; F = few ; R = rare.
For preservation, G = good

age is taken from Young's (1999) compilation, and has
been calibrated with magnetostratigraphy in different
oceans (see Wei, 1995, p.296, fig.6);
the top of Reticulofenestra rotaria at 6.1Ma (age from
Young's (1999) compilation). This study provides
probably the first documentation of the species in the
Gulf ofMexico (Table 1);
the top of Discoaster berggrenii at 6.2?Ma. The age
is a rough estimate based on a slightly lower stratigraphic level than the top of R. rotaria (6.1Ma) inCore CH30-43-2 (Table 1). See taxonomic discussion
below for the species concept of D. berggrenii;
the top of Discoaster loeblichii at 6.6Ma (age from
Young's (1999) compilation); the top of Discoaster
berggrenii extensus at 6.6?Ma. The latter age is arough estimate based on the eo-occurrence of thedatum with the top of D. loeblichii in Core CH30-43-2(Table 1), although current sample resolution is insufficient to reveal the precise relationship between thetwo datums. See taxonomic discussion below for thedefinition of the new subspecies (D. berggrenii
extensus);
the top of Discoaster bergenii at 7.2?Ma; the bottomof the Amaurolithus primus-A. delicatus group at
7.2Ma(age from Young, 1999). The age for the top of
D. bergenii is a rough estimate based on the eo-occurrence ofthe datum with the bottom of the A. primusA. delicatus group in Core CH30-43-2 (Table 1). Cur-rent sample resolution is insufficient to reveal the precise relationship between the two datums. See taxonomic discussion below for the species concept of D.
bergenii;
the tops of Minylitha convallis and Discoasterneohamatus and the bottom of Discoaster surculus
at7.8Ma(agefromYoung, 1999);
the bottoms of D. berggrenii and D. bergenii at
8.2?Ma. This age is based on their stratigraphic position (Table 1) between the tops of M convallis and D.
neohamatus (7.8Ma) and the bottom of Discoaster
quinqueramus (8.5Ma: Young, 1999);
the bottom of Discoaster quinqueramus at 8.5Ma (agefrom Young, 1999);
the top of the first Reticulofenestra pseudoumbilicus(>7f.Lm) at 9.0Ma (age from Young, 1999). This may
also be called the bottom of an upper Miocene interval without R. pseudoumbilicus (>7f.Lm);the top of Discoaster prepentaradiatus and the bottom of Discoaster loeblichii at 9.2?Ma. This age isestimated based on their stratigraphic position (Table
1) between the top of the first R. pseudoumbilicus(>7f.Lm) at 9.0Ma and the top of Discoaster hamatus(9.4Ma: Young, 1999);
the top of Discoaster hamatus at 9.4Ma (Young, 1999);
the tops of Discoaster bollii, D. wisei and Catinastercoalitus, and the bottom of D. pentaradiatus at
9.4 ?Ma. The latter age is a rough estimate based on

18

Journal ofNannoplankton Research, 25 , I, 2003.

W Wei: Upper Miocene biostratigraphy... , p. 17 - 23.

the eo-occurrence of these datums with the top of D.
hamatus (9.4Ma) in Core CH30-43-2 (Table 1), althoughsample resolution is insufficient to reveal the precise
relationship among these datums.
It is interesting to note that this Upper Miocene
interval of over 2my duration is found within about 4m ofcore, and thus it appears to be an unusually condensed
interval. Explanations might include coring artefact, significant hiatuses, and very low sedimentation rates overthis interval. Since the interval was captured within one
core, and there is a remarkable succession of multiple
nannofossil datums through the interval, omission of significant core material or presence of significant hiatuses
within· the core appears to be unlikely. The more likely
explanation is truly low sedimentation rates due to prevailing palaeoceanographic conditions (e.g. strong currents,
winnowing, etc.) at the site in the Late Miocene. This may
have significant palaeoceanographic implications, but the
subject is beyond the scope of the present article.
4. Taxonomy

Discoaster quinqueramus-D. berggrenii-D. bergenii
group: It has been widely known ~r assumed that there ismorphological gradation among the taxa within this group.
However, it has been unclear or there have been large disagreements about the species concepts and the sequenceof species events for different taxa within this group. For
instance, D. bergenii has been rarely reported in the literature and the species was not included in some of the mostcomprehensive treatments of the genus or the group (e.g.
Perch-Nielsen, 1985; Raffi et al., 1998). There has been
considerable confusion in the literature about the difference between D. berggrenii and D. quinqueramus. Only
the top and bottom of the group have been commonlyused for biostratigraphy (Martini, 1971; Perch-Nielsen,
1985; Young, 1999).
Here, some of the more distinct, and presumably
the more useful, species and subspecies of the group are

Nannofossil datum Age (Ma)6

-1.-...J---! -,--D. quinqueramus 5.6-,--R. rotaria 6.1-,D. berggrenii berggrenii 6.2?

- ,D. loeblichii 6.6, D. berggrenii extensus 6.6?
__j_

8

9

Amaurolithus spp. 7.2

D. neohamatus, M. convalis 7.8

D. surcu/us 7.8__j___j_D. berggrenii berggrenii 8.2?
D. quinqueramus 8.5

pseudoumbilicus (>7Jlm) 9.0-,D. prepentaradiatus 9.2?
__j_D. loeblichii 9.2-,D. hamatus 9.4 D . coalitus, D. wisei, D. bollii 9.4?

10
Figure 2: Summary of Upper Miocene nannofossil datums andtheir ages that may be applicable in the Gulf of Mexico. Ages are
given in the time-scale of Berggren et al. (1995). See text for
discussion of individual datums and ages

19

documented in both micrographs (Plate 1, Figures I -8) andthe range-chart (Table 1). A total of six species-events
within the group can be used to subdivide the Late Miocene in the Gulf of Mexico (Figure 2), when the species
concepts described below are adopted.
Discoaster bergenii (Plate 1, Figure l ): A
disco aster with five tapering, non-bifurcated rays, a prominent inter-ray star, which frequently extends beyond thecentral area, and with the free rays of the discoaster up tohalf of the diameter of the central area.
Discoaster berggrenii berggreniin. subsp. (Plate
1, Figures 4, 5): A discoaster with five tapering, non-bifurcated rays, a prominent inter-ray star (see SEM micrographofPerch-Nielsen, 1985, fig.33.8) on the distal side, a prominent, 5-element central knob on the proximal side, and withthe five elements aligned with the rays ofthe discoaster;
the free rays of the discoaster are longer than half of thediameter of the central-area.
Discoaster berggrenii extensus n. subsp. (Platel, Figures 2, 3): A subspecies ofD. berggreniiwith a prominent inter-ray star slightly extending beyond the central
area. It differs from D. bergenii in having longer free rays
(longer than half of the diameter of the central area) andfrom D. berggrenii berggrenii by possession of a prominent inter-ray star slightly extending beyond the centralarea, and shorter free rays (50-100% the diameter of thecentral area).
Discoaster quinqueramus (Plate 1, Figures 7, 8):
A discoaster with five tapering, non-bifurcated rays and aprominent, five-element central knob; the five elements ofthe central knob are aligned with the rays of the discoaster(see SEMmicrograph ofPerch-Nielsen, 1985, fig.33.9). The
species lacks a distal inter-ray star, which is present in D.
berggrenii and D. bergenii, and this is probably the mostfundamental difference between D. quinqueramus and D.
berggrenii or D. bergenii. The free rays of the discoasterin D. quinqueramus are longer than the diameter of thecentral-area. In other words, D. berggrenii can be easily
distinguished from D. quinqueramus by having an interray star, the elements of which are aligned between the
discoaster rays rather than aligned with the discoaster
rays, as in the central knob in D. quinqueramus. Furthermore, the central-area of D. quinqueramus is generally
minimal, or practically non-existent, whereas the centralarea is relatively wide (up to two times the length of the
discoaster rays) in D. berggrenii.
Other new taxonomic observations from Core
CH30-43-2 are described below (in alphabetical order):Discoaster pentabolliin. sp. (Plate 1, Figures 13,14): Similar to Discoaster bollii but with only five rays,
rather than six rays as in the latter species. The former
species probably has been included in the latter one insome previous studies. Here, it has been separated out asa new species because: (1) it can be easily distinguishedfrom the latter species; (2) sufficient specimens (> l 0) occur in one sample to allow a reasonable understanding of
its general characteristics; and (3) its biostratigraphic range
and palaeoecological parameters are likely to be different
from those of D. bollii and thus it may be potentially valuable to record the species separately.
Discoaster prepentaradiatus emended (Plate 2,

Journal of Nannoplankton Research, 25, I, 2003.

Figures 3, 4): The original (Bukry & Percival, 1971) andsubsequent descriptions of this species all emphasised
the bifurcations of the rays but with no mention of a central knob. However, many specimens of this species do
not show bifurcations Uust as many specimens of
Discoaster pentaradiatus do not show bifurcations) andmany specimens of D. prepentaradiatus have a central
knob (see Plate l, Figure 4).
Discoaster neohamatus: The original descriptionof this species (Bukry & Bramlette, 1969) gave a size-rangeof 10-l5f.Lm. Here, specimens as large as 30f.Lm (Plate 1,
Figure 15), twice the size of the maximum value originallygiven, are docwnented and thereby the size-range of thisspecies is emended.
Discoaster styzenii n. sp. (Plate 2, Figures 5-8): A
discoaster with four slender, tapering rays. Typically, therays are bifurcated at the ends, the discoaster is asymmetrical, and there is a knob in the central area (although
not all these features are present in some specimens). Thesefeatures differ from those ofDiscoaster tamalis. The latter
species is limited to the Late Pliocene (e.g. Perch-Nielsen,
1985; Young, 1999), and the two species do not overlap instratigraphy. This species has also been observed in the
Discoaster hamatus zone (CN7 or NN9) of the Cipero section, Trinidad.
Discoaster wisei (Plate 2, Figures 9-12, 19): A sixrayed discoaster with prominent central ridges extending
to the ends of the rays. The central-area is relatively large,
with no prominent central star or knob (only an indistinct
star or knob in some specimens). This species has also
been observed in the D. hamatus zone (CN7 or NN9) of the
Cipero·section, Trinidad.

slightly beyond the central area, and shorter free ra) -o100% of the diameter of the central area).
Occurrence: This subspecies has a shorter stratigraphic
range than D. berggrenii ssp. berggrenii, with its top nearthat of Discoaster loeblichii at about 6.6Ma.
Holotype: Plate 1, Figure 2 (FSU-CH30-43-2-1-2).
JYpe locality: Exxon Corehole CH30-43 in the GulfofMexico(28°01.1 'N, 86°24.7'W), Sample CH30-43-2, 1.85-1.88m.

Discoaster pentabollii n. sp.
Plate 2, Figures 13, 14
Derivation of name: Penta, refers to the five rays of the
discoaster.
Description: Five-rayed discoaster with a large, stellate
stem and a relatively large central-area. The rays are bifurcated.
Remarks: This species is most similar to Discoaster bollii(most likely recorded as such in previous studies) but isquite distinct in having five rays, rather than six rays as in
the latter species. It differs from other five-rayed discoasters
by possessing a large, stellate stem, relatively large central-area, and bifurcated rays.
Occurrence: This species has been found in CN7 or NN9.
Holotype: Plate 1, Figure 14 (FSU-CH30-43-2-1-14).
Type locality: Exxon Corehole CH30-43 in the Gulf ofMexico(28°01.1 'N, 86°24.7'W), Sample CH30-43-2, 4.27-4.29m.

Discoaster prepentaradiatus Bukry & Percival, 1971,
emendedPlate 2, Figures 3, 4
Discoaster prepentaradiatus Bukry & Percival, 1971 : p.l29,
p1.3 , figs 6, 7.

5. Systematic palaeontology
Genus Discoaster Tan, 1927
Discoaster berggrenii ssp. berggrenii n. subsp.
Plate 1, Figures 4, 5
Description: A subspecies of D. berggrenii with free raylength which is longer than the diameter of the central
area.
Remarks: This subspecies has a longer stratigraphic range
than the subspecies Discoaster berggrenii extensus n.
subsp. (see below).
Holotype: Pl.2, fig.6 ofBukry ( 1971 ).
Type locality: DSDP 3-9-3,75 cm, GulfofMexico.

Discoaster berggrenii ssp. extensus n. subsp.
Plate 1, Figures 2, 3
Derivation of name: Latin, extensus, extend, referring to
the inter-ray star extending beyond the central area.
Description: A subspecies of D. berggrenii with a prominent inter-ray star extending beyond the central area. Its
free rays are between 50 and 100% ofthe diameter ofthe
central area.
Remarks: This subspecies differs from D. bergenii bypossessing longer free rays (longer than half of the diameter of the central area) and from D. berggrenii ssp.
berggrenii by having a prominent inter-ray star, extending

Description: Medium-sized, long-rayed, with virtually nodeveloped central area and five rays in one plane. Rays
commonly show widely-splayed, short bifurcations. Unlike Discoaster pentaradiatus, it shows uniform low birefringence in cross-polarised light.
Remarks: The original (Bukry & Percival, 1971) and subsequent descriptions of this species all emphasised thebifurcation of the rays but with no mention of a central
knob. However, many specimens of this species do notshow bifurcations Gust as many specimens of Discoasterpentaradiatus do not show bifurcations), and many specimens of D. prepentaradiatus have a central knob. It differs from D. pentaradiatus by showing uniform birefringence, whereas D. pentaradiatus discoasters show slightly
different birefringence of each ray.
Occurrence: This species has a relatively short stratigraphic range, within CN7-CN8.

Discoaster neohamatus Bukry & Bramlette, 1969,
emendedPlate 1, Figures 15, 16
Discoaster neohamatus Bukry & Brarnlette, 1969: p.l33 , pi. I,

figs 4, 5.
Description: Medium- to large-sized, six slender rays all

20

W. Wei: Upper Miocene biostratigraphy... , p. 17 - 23.

Journal of Nannop lankton Research , 25, I, 2003 .

bending consistently in one direction and terminating inpoints. Central area small with no knob.
Remarks: The original description of this species (Bukry& Bramlette, 1969) gave a size-range of 10-15J.!m. The sizeof this species is emended here to range up to 30J.!m (large
size )(see Plate 1, Figure 15).
O~currence: CN7-CN9.

Discoaster styzenii n. sp.
Plate 2, Figures 5-8
Derivation of name: In honour ofMichael Styzen for his
significant contribution to Gulf of Mexico Neogene
nannofossil biostratigraphy.
Description: A discoaster with four slender, tapering rays.
Typically, the rays are bifurcated at the ends, the discoasteris asymmetrical, and there is a knob in the central-area.
Remarks: This species is similar to Discoaster tamalis,but differs from the latter by its asymmetric and bifurcatedrays, and the presence of a central knob (although not allof these features are present in some specimens of D.
styzenii). D. tamalis is limited to the Upper Pliocene (e.g.
Perch-Nielsen, 1985; Young, 1999) and the two species do
not overlap in stratigraphy. It differs from another fourrayed Neogene discoaster, Discoaster quadramus (Bukry,
1973), in having asymmetric rays rather than the regularangles of60° and 120° in D. quadramus. The latter species
was described from the Pliocene (Bukry, 1973), and is probably limited to the Pliocene, whereas D. styzenii appears to
be limited to the Miocene.
Occurrence: Discoaster styzenii has been observed in
CN7-CN9 in Core CH30-43-2 in the Gulf ofMexico and in
CN7 of the Cipero section, Trinidad.
Holotype: Plate 2, Figure 8 (FSU-CH30-43-2-2-8).
Type locality: Exxon Corehole CH30-43 in the GulfofMexico(28°01.1 'N, 86°24.7'W), SampleCH30-43-2, 3.78-3.81m.

Disco aster wisei n. sp.
Plate 2, Figures 9-12, 19
Derivation of name: In honour of Sherwood W. Wise, Jr.
for his significant contribution to nannofossil
palaeontology, especially in nannofossil education.
Description: Six tapering rays with prominent central ridges
extending to the end of the rays. The central-area is relatively large, with no prominent central star or knob.
Remarks: This species is quite distinctive, with its prominent central ridges and relatively large central-area, anddiffers from other large-bodied, six-rayed discoasters by
the lack of a prominent central star or knob, as in Discoastermusicus/Discoaster sanmiguelensis, and Discoasterintercalaris. It differs from Discoaster exilis in possessing a relatively large central-area and prominent central
ridges; D. exilis has a very small central-area, and faintridges extending radially to one side of the median line.
Occurrence: Discoaster wisei has been observed in CN7
in Core CH30-43-2 in the Gulf of Mexico, as well as in the
Cipero section, Trinidad.
Holotype: Plate 2, Figures 10, 11 (FSU-CH30-43-2-2-1 0, FSUCH30-43-2-2-11).

21

Type locality: Exxon Corehole CH30-43 in the Gulf ofMexico(28°01.1 'N, 86~4.7'W), Sample CH30-43-2, 4.27-4.29m.
Acknowledgments
I thank Prof. S. W. Wise (FSU) for making the material available for this study and providing relevant information. I
also wish to thank T.C. Huang (ExxonMobil) and M. Styzen(Shell) for useful comments and suggestions. The helpful
editorial reviews ofJ. Young and J. Lees are also gratefully
acknowledged.
References
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Weiterman, S.D. 1989. Neogene calcareous nannofossil biostratigraphy ofthe West Florida Carbonate Ramp Slope, Northeast Gulf of Mexico. MS thesis, Florida State University.
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Nannofossil Biostratigraphy. Chap man & Haii!Kiuwer Academic, Cambridge: 225-265.

W Wei: Upper Miocene b~

Journal of Nannoplankton Research , 25, I, 2003 .

Plate 1
All images have the same magnification, which is indicated by the scale-bar

D. bergenii

D. berggrenii extensus

D. berggrenii extensus D. berggrenii berggrenii

D. berggrenii berggrenii D. berggrenii berggrenii

D. quinqueramus

.

.

• '.

•.

I

~"·':

~-,· k9
A. delicatus

D. quinqueramus

A. delicatus

D. neohamatus

D. bollii

10 J.UTl

D. neohamatus

12 ' D. bollii

D. hamatus

Fig. I: Discoaster bergenii. Sample CH30-43-2, 1.85-1 .88m. Fig 2,3: Discoaster berggrenii extensus n. subsp. Sample
CH30-43-2, 1.85-1 .88m; 2, holotype. Fig 4-6: Discoaster berggrenii berggrenii n. subsp. Sample CH30-43 -2, 0.91 0.94m; 5, 6, same specimen, 5, focus on the inter-ray star on the distal side, 6, focus on the knob on the proximal side.
Figs 7, 8: Discoaster quinqueramus. Sample CH30-43-2, 0.91-0.94m. Figs 9, 10: Amaurolithus de/icatus. Sample CH3043-2, 0.91-0.94m. Figs 11, 12: Discoaster bol/ii. Sample CH30-43-2, 4.27-4.29m. Figs 13, 14: Discoaster pentabolliin. sp.
ample CH30-43-2, 4.27-4.29m; 14, holotype. Figs 15, 16: Discoaster neohamatus. Sample CH30-43-2, 3.35-3.38m.
Fig.l7: Discoaster hamatus. Sample CH30-43-2 4.27-4.29m.

22

Journal ofNannoplankton Research, 25, I, 2003 .

W We/: Upper Miocene bioslnltigraphy... , p. 17 - 23 .

Plate 2

D. loeblichii

D. pentaradiatus

D. prepentaradiatus

D. prepentaradiatus

I,..,,.:)\-.

6
D. styzenii

D. styzenii

D. styzenii

D. styzenii

D. wisei

D. wisei

D. wisei

D. wisei•.
-d.

: . am~~18

R. rotaria

A. amplificus·.

A. ampliflcus

10 f..UD.

.

D. wiseiFig.1: Discoaster loeblichii. ample CH30-43-2, 3.35-3.38m. Fig.2: Discoaster p entaradiatus. Sample CH30-43-2, 3.353.38m. Figs 3, 4: Discoaster prep entaradiatus. Sample CH30-43-2, 3.78-3.81 m. Figs S-8: Discoaster styzenii n. sp.
Sample CID0-43-2 3.78-3.81 m; 8, holotype. Figs 9-12, 19: Discoaster wisei n. sp. ample CID0-43-2, 4.27-4.29m; I 0, 11(holotype), same specimen with different focus levels; 12, 19, same specimen with different focus levels. Fig 13-16:
Reticulofenestra rot aria. Sample CH30-43-2, 0.46-0.48m (13, 14); sample CH30-43-2, 0.9l-0.94m (15, 16). Fig 17, 18:
Amaurolithus amplificus. Sample CH30-43-2, 0.46-0.48m.

23